Austin bomb an amateur job or something more insidious?

Story highlights

Someone on a cigarette break spotted a container outside a dumpster, called 911

Authorities determined it included a bomb that had ammonium nitrate

It could have been part of "something bigger, or it could be juvenile," investigator says

A homemade bomb was found outside a business complex in Austin, Texas, authorities said, speculating that it might have been anything from a crude experiment to a dry run for something bigger and more deadly.

"It could be something where someone is preparing for something bigger, or it could be juvenile," said Austin chief arson investigator Aaron Woolverton.

Late on April 21, just before midnight, a person saw an object -- later determined to be the quart-size container that held the explosive -- on the ground near a trash container, Woolverton told CNN on Thursday. The witness walked over with a bucket of water to extinguish what looked to be a small fire, then went back inside a building.

The next day, around 1 p.m., a person on a cigarette break spotted the container and called 911. Bomb squad members safely disabled the object, fragments of which were studied to determine what was inside.

Authorities this week provided additional details on the incident.

Initial tests showed the device contained ammonium nitrate, the same volatile substance that sparked a massive explosion last month at a fertilizer distribution plant 110 miles north in West, Texas, said Austin fire Lt. Randy Elmore. He called the apparatus "a legit system."

Woolverton said his office believes it was an "experiment," given that it looked "more amateur."

No one has claimed responsibility, and no one has been arrested. Authorities are asking for the public's help in their investigation, while not ruling out that this might conceivably be tied to a larger plot.